CN118401214A - Use of C20-36 fatty alcohols for producing O/W emulsions having low viscosity - Google Patents

Abstract

Use of a C20-36 fatty alcohol to prepare an O/W emulsion having a lower viscosity than an O/W emulsion wherein the C20-36 fatty alcohol is replaced by a C16-18 fatty alcohol. O/W emulsions and methods of making O/W emulsions having lower viscosities are also provided.

Description

Use of C20-36 fatty alcohol in the preparation of O/W emulsions with low viscosity

Technical Field

The present invention relates to the application of C20-36 fatty alcohol in oil-in-water (O/W) emulsion.

Background technique

As is known to all, when formulating O/W emulsions, long chain fatty alcohols with a carbon chain length of 16-18 are often added to stabilize the emulsion, increase viscosity and obtain a better texture. Adding about 1-3 wt% of long straight chain fatty alcohols to the emulsifying system increases the viscosity of the formulation and makes the emulsion formulation more stable.

However, there is a need for low viscosity emulsions in the market. Formulators are facing the problem of high viscosity caused by using (C16-C18) alkyl alcohols (cetostearyl alcohol) to stabilize low viscosity emulsions. In addition, high viscosity will make the manufacturing process difficult and will make it impossible to prepare low viscosity emulsion products.

Summary of the invention

It is an object of the present invention to at least partially overcome the viscosity problems caused by the use of C16-18 fatty alcohols in O/W emulsions.

According to the prior art, it is believed that C20-36 fatty alcohols have a higher melting point than C16-C18 fatty alcohols and should therefore have a higher viscosity increasing effect. However, the inventors surprisingly found that when the carbon number of the fatty alcohols increases, for example, from C16-18 to C20-36, the viscosity increasing effect is much lower than that of traditional long-chain fatty alcohols, but the effects of long-chain fatty alcohols (e.g., stabilizing the emulsion) are maintained. Therefore, such C20-36 fatty alcohols are particularly suitable for preparing O/W emulsions with relatively low viscosity.

The present invention provides the use of C20-36 fatty alcohol to prepare an O/W emulsion having a lower viscosity than an O/W emulsion in which the C20-36 fatty alcohol is replaced by a C16-18 fatty alcohol.

Therefore, the present invention provides a method for preparing an O/W emulsion having a lower viscosity than an O/W emulsion with a C16-18 fatty alcohol, wherein the O/W emulsion is prepared using a C20-36 fatty alcohol, preferably replacing the C16-18 fatty alcohol.

It is obvious that the term "replacement" in the aforementioned terms refers to the replacement of the same amount of C16-18 fatty alcohol in terms of weight.

The C16-18 fatty alcohol to be replaced in this context is a mixture consisting of 50% by weight of C16 linear alkanol and 50% by weight of C18 linear alkanol.

The present invention provides an O/W emulsion comprising:

a) 0.5% to 10% by weight of a C20-36 fatty alcohol, based on the total weight of the emulsion.

The C20-36 fatty alcohol may be a mixture of fatty alcohols having a carbon number of 20 to 36, such as 20 to 34, 20 to 32, 20 to 30, 24 to 36. A mixture of fatty alcohols may result in an even lower viscosity in the emulsion than a single fatty alcohol. The C20-36 fatty alcohol is preferably a mixture of fatty alcohols having a carbon number selected from 20 to 36, and the amount of C20-30 fatty alcohol is greater than 30 wt%, 40 wt% or 50 wt%, preferably greater than 60 wt%, greater than 70 wt%, more preferably greater than 80 wt%, greater than 90 wt%, greater than 95 wt%, greater than 99 wt%, wherein the weight percentages are with respect to all fatty alcohols contained in the C20-36 fatty alcohol. The C20-36 fatty alcohol is more preferably a mixture of fatty alcohols having a carbon number selected from 20 to 36, and the amount of C20-28 fatty alcohol is greater than 15%, 18% or 20%, preferably greater than 30%, greater than 40%, more preferably greater than 50%, greater than 60%, greater than 70%, greater than 80%, greater than 90%, greater than 95% or greater than 99%, wherein the weight percentages are with respect to all fatty alcohols contained in the C20-36 fatty alcohol.

The two mixtures of the above-mentioned fatty alcohols having a carbon number selected from 20 to 36 preferably contain at least 3, more preferably at least 4, different fatty alcohols having a carbon number selected from 20 to 30 or 20 to 28, respectively.

The emulsion preferably comprises at least 90% by weight, preferably at least 95% by weight, more preferably at least 95% by weight of C20-36 fatty alcohol, wherein the weight percentages relate to all fatty alcohols contained in the total emulsion.

The emulsion preferably contains no C16-18 fatty alcohol.In some embodiments, the emulsion contains no other long chain fatty alcohols other than the C20-36 fatty alcohol used.

Preferably, the emulsion does not contain monounsaturated straight chain or saturated branched chain acids having at least 18 carbon atoms.

Preferably, the emulsion contains no other viscosity increasing agents.

Preferably, the emulsion comprises 1 wt% to 5 wt% O/W emulsifier, based on the total weight of the emulsion.

In the context of the present invention, the term "C20-36 fatty alcohol" refers to at least one fatty alcohol selected from fatty alcohols having a number of carbon atoms in the range of 20 to 36. Thus, for example, pure C24 fatty alcohol is considered a "C20-36 fatty alcohol".

In the context of the present invention, the term "fatty alcohol" preferably refers to primary branched and straight-chain alkanols and alkenols, preferably straight-chain alkanols.

The C20-36 fatty alcohol may have a carbon chain length of 20-35, 20-34, 20-33, 20-32, 20-31, preferably 20-30, such as 20-29, 20-28, more preferably 20-26, such as 20-24 or 20-22. Thus, the C20-36 fatty alcohol may include any CX-Y fatty alcohol, wherein X and Y are integers from 20 to 36, X>=20, Y<=36 and X<Y. When the C20-36 fatty alcohol has a carbon chain length Z of less than 36, such as 20-26, it may also be described as a C20-Z fatty alcohol, such as a C20-26 fatty alcohol. Specific examples of C20-36 fatty alcohols include eicosanol (C20), docosanol (C22), tricosanol (C23), tetracosanol (C24), pentacosanol (C25), hexacosanol (C26), heptacosanol (C27), octacosanol (C28), triacontanol (C30), dotriacontanol (C32), tritriacontanol (C33), tetratriacontanol (C34), hexatriacontan-1-ol (C36), and mixtures thereof. In some embodiments, 1-eicosanol, 1-docosanol, 1-tetracosanol, 1-hexacosanol, 1-octacosanol, triacontanol, 1-triacontanol, or mixtures thereof are used as C20-36 fatty alcohols.

Preferably, the C20-36 fatty alcohol in the context of the present invention is a mixture containing tetracosanol, hexacosanol, octacosanol, triacontanol, dotriacontanol and tetratriacontanol, wherein octacosanol, triacontanol and dotriacontanol account for at least 50% by weight of all C20-36 fatty alcohols.

The term "long-chain fatty alcohol" in the present invention refers to a fatty alcohol having a carbon number equal to 14 or more.

The emulsifier of the O/W emulsion can be selected from conventional emulsifiers suitable for preparing O/W emulsions. The emulsifier can be selected from, for example, polyglycerol ester emulsifiers, anionic emulsifiers, polyethylene glycol (PEG) emulsifiers and sugar-based emulsifiers.

The polyglycerol ester emulsifier can be selected from esters with a degree of polymerization of polyglycerol in the range of 2 to 16, preferably 3 to 10. The polyglycerol in the polyglycerol ester emulsifier is preferably esterified with a carbonate containing at least one fatty acid, the fatty acid preferably having a carbon chain length selected from 6 to 30 carbon atoms, preferably 10 to 18 carbon atoms. The degree of esterification of the polyglycerol ester emulsifier is preferably in the range of 1 to 12, preferably 1 to 6.

The polyglycerol ester emulsifier may preferably be selected from

Long-chain polyglycerol esters having fatty acid moieties from the chemical class of linear or branched, saturated or unsaturated fatty acids with a chain length of C14-C30, preferably C15-C24, particularly preferably C16-C20; and

Short chain polyglycerol esters prepared from linear or branched, saturated or unsaturated fatty acids with a chain length of C8-C12, preferably C10-C12.

An alternative preferred polyglycerol ester emulsifier is a polyglycerol esterified with a mixture of fatty acids containing at least 70% by weight of behenic acid and lignoceric acid, wherein the weight percentages are related to all carbonic acids esterified with the polyglycerol. Preferably, in this context, the weight ratio of behenic acid to lignoceric acid is preferably in the range of 1:1 to 1:3, preferably 1:1.5 to 1:2.

Such alternative preferred polyglycerol ester emulsifiers preferably have a degree of esterification in the range of 1 to 3, preferably 1.2 to 2.0, more preferably 1.3 to 1.8.

Examples of polyglycerol ester emulsifiers may be any one or more selected from the following:

Polyglyceryl-6 Stearate,

Polyglyceryl-6 behenate, such as HYDROGENOL® from Evonik Industries AG CARE PBS 6 (Polyglyceryl-6 Stearate (and) Polyglyceryl-6 Behenate),

Polyglyceryl-3 distearate, such as from Evonik Industries AG NC MB (Polyglyceryl-3 Distearate; Glyceryl Stearate Citrate),

Candelilla wax/jojoba/rice bran polyglyceryl-3 esters, such as Emulium Kappa MB (candelilla wax/jojoba/rice bran polyglyceryl-3 esters (and) glyceryl stearate (and) cetearyl alcohol (and) sodium stearoyl lactylate) from Gatteforsse,

Polyglyceryl-4 laurate (commercially available from Evonik under the trade name CARE PL4),

Polyglyceryl-6 Laurate,

Polyglyceryl-6 Caprylate/Caprate, and

Polyglyceryl-3 caprylate/caprate.

The anionic emulsifiers in the present invention are preferably selected from alkyl sulfates, alkyl ether sulfates, optionally alkoxylated sulfosuccinates, optionally alkoxylated methylsulfosuccinates, optionally alkoxylated sulfonates, optionally alkoxylated glycinates, optionally alkoxylated glutamates, optionally alkoxylated isethionates, optionally alkoxylated carboxylates, optionally alkoxylated anisates, optionally alkoxylated levulinates, optionally alkoxylated tartrates, optionally alkoxylated lactates, optionally alkoxylated taurates, optionally alkoxylated alanates, optionally alkoxylated phosphates, optionally alkoxylated sulfoacetates, optionally alkoxylated sulfosuccinamates, optionally alkoxylated sarcosinates and optionally alkoxylated phosphonates, preferably optionally alkoxylated sulfonates, alkyl sulfates, alkyl phosphates and alkyl ether sulfates.

Examples of anionic emulsifiers may be any one or more selected from the following:

Potassium cetyl phosphate (such as from Clariant CK 100 or from DSM K),

Sodium Lauryl Sulfate,

Sodium cetearyl sulfate, such as from BASF SX (Cetearyl Alcohol (and) Sodium Lauryl Sulfate (and) Sodium Cetearyl Sulfate).

The PEG emulsifier is preferably selected from ethoxylated fatty acids and ethoxylated fatty alcohols.

Examples of PEG emulsifiers may be any one or more selected from the following:

PEG-100 stearate, such as SIMULSOL ^™ 165 (PEG-100 stearate (and) glyceryl stearate) from SEPPIC.

The sugar-based emulsifier may be selected from alkyl polyglucosides, alkyl glucosides, sorbitan esters, sorbitol esters, sucrose esters, methyl glucoside esters and fatty acid gucamides. The esters listed above are preferably fatty acid esters.

The alkyl polyglucoside includes an alkyl polyglucoside having an alkyl modification selected from the chemical class of linear or branched, saturated or unsaturated fatty alcohols with a chain length of C12 to C22, preferably C16 to C18; preferably, the alkyl polyglucoside has a glucoside polymerization degree of>1 and ≤2, more preferably 1.0 to 1.7.

Examples of sugar-based emulsifiers may be any one or more selected from the following:

Cetearyl Glucoside (commercially available from Evonik under the trade name Care CG 90),

Coco-glucoside, such as MOTANOV ^™ S (coco-glucoside (and) coconut alcohol) from SEPPIC, and

Myristyl glucoside, such as MOTANOV ^™ 14 (myristyl alcohol (and) myristyl glucoside) from SEPPIC.

Based on the total weight of the emulsion, the amount of C20-36 fatty alcohol is 0.5-10 wt%, such as 0.5-9 wt%, 0.5-8 wt%, 0.5-7 wt%, 0.5-6 wt%, 0.5-5 wt%, 0.5-4 wt%, 0.5-3.5 wt%, 0.8-9 wt%, 0.8-8 wt%, 0.8-7 wt%, 0.8-6 wt%, 0.8-5 wt%, 0.8-4 wt%. %, 0.8-3.5 wt %, 1-9 wt %, 1-8 wt %, 1-7 wt %, 1-6 wt %, 1-5 wt %, 1-4 wt %, 1-3.5 wt %, preferably 0.5-3 wt %, 0.8-3 wt %, or 1-3 wt %, for example 0.5-2.5 wt %, 0.5-2 wt %, 0.8-2.5 wt %, 0.8-2 wt %, 1-2.5 wt %, 1-2 wt %.

Preferably, the weight ratio of C20-36 fatty alcohol to emulsifier is in the range of 2:1 to 0.5:1, more preferably 1.5:1 to 1:1, most preferably 1.35:1 to 1.1:1.

In some embodiments, the O/W emulsion comprises the following components by mass percentage:

1%-5% O/W emulsifier

1%-10% C20-36 fatty alcohol,

5%-30% moisturizing fat,

60%-80% water,

0.1%-5% preservatives, and

1%-10% glycerin.

The emulsion according to the invention may comprise, for example, at least one additional component selected from emollients,

Emulsifiers,

Thickener/Viscosity Conditioner/Stabilizer,

UV light protection filters,

Antioxidants,

Hydrotrope (or polyol),

Solids and fillers,

Film formers,

Pearlescent additives,

Deodorant and antiperspirant active ingredients,

Insect repellent,

Self-tanning agents,

preservative,

Conditioning agents,

spices,

dye,

Odor absorbers,

Cosmetic active ingredients,

Care additives,

Superfatting agents,

Solvent.

Substances which can serve as exemplary representatives of the individual groups are known to the person skilled in the art and can be found in the German application DE 102008001788.4. This patent application is incorporated herein by reference and thus forms part of the present disclosure.

With regard to further optional components and the amounts of these components to be used, reference is expressly made to the relevant handbooks known to the person skilled in the art, for example K. Schrader, “Grundlagen und Rezepturen der Kosmetika [Fundamentals and Formulations of Cosmetics]”, 2nd edition, pages 329 to 341, Hüthig Buch Verlag Heidelberg.

The emulsion according to the invention preferably comprises free fatty acids or their salts, preferably long-chain fatty acids, more preferably a mixture of C22 and C24 fatty acids, even more preferably in salt form. The amount of fatty acids contained in the emulsion according to the invention is preferably in the range of 10 to 20% by weight, wherein the weight percentages are with respect to the total emulsion. If free fatty acids are included in the form of salts, the weight percentages are calculated without taking into account the weight of the cations.

For the preparation method of the emulsion according to the present invention, due to the high melting point (about 80-90° C.) of C20-36 fatty alcohol, it is necessary to add the molten C20-36 fatty alcohol to the oil phase to completely dissolve it, and then perform the subsequent routine of the O/W emulsion preparation process.

Therefore, according to the present invention, C20-36 fatty alcohols have a reduced viscosity increasing effect compared to C16-18 fatty alcohols, but can stabilize O/W emulsions, provide co-emulsification ability and viscosity increasing effect.

Other advantages of the present invention will become apparent to those skilled in the art after reading the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the viscosity of the emulsions prepared in Examples and Comparative Examples.

Detailed ways

The present invention will now be described in detail by way of the following examples. The scope of the present invention should not be limited to the embodiments of the examples.

The emulsion in the specification is prepared according to the following method,

1) Add the ingredients of phase A according to the listed formula into a beaker and heat the ingredients of phase A to 85°C.

2) Add the ingredients of phase B to another beaker and heat the ingredients of phase B to about 85°C.

3) Mix phase A and phase B and homogenize with a homogenizer at high speed for 3 minutes.

4) Add the ingredients of phase C and stir for 3 minutes, and

5) Cool while stirring, add the ingredients of phase Z (and phase D, if any) below 40°C and stir for a while until a homogeneous emulsion is obtained.

The viscosity of the prepared emulsion was measured using Brookfield RVT, S93, 10 rpm, 10 s.

In an embodiment, using Care CG 90 as cetearyl glucoside is commercially available from Evonik Industries AG.

As C20 fatty alcohol, 1-eicosanol (C ₂₀ H ₄₂ O>95 wt%) was used, which is commercially available from Tokyo Chemical Industry.

As C22 fatty alcohol, 1-docosanol (C ₂₂ H ₄₆ O>98 wt%) was used, which is commercially available from Tokyo Chemical Industry.

1-Octacosanol (C ₂₈ H ₅₈ O>90 wt %) was used as the C28 fatty alcohol, which is commercially available from Ourchem (Sinopharm Chemical Reagent Co., Ltd.).

Triacontanol (C ₃₀ H ₆₂ O>90 wt %) was used as the C30 fatty alcohol, which is commercially available from Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China).

As the mixed C20-C36 fatty alcohol, policosanol commercially purchased from Huzhou Shengtao Biotech LLC (Zhejiang, China) was used. According to GC-MS measurement, policosanol contains C24-C34 fatty alcohol as a main component, and it also contains a small amount of C36 fatty alcohol.

use Alkanol 1618 as cetearyl alcohol is commercially available from Evonik Industries AG.

use PC serves as a preservative and is commercially available from Evonik Dr. Straetmans GmbH.

use NC MB serves as an O/W emulsifier, which is commercially available from Evonik Industries AG.

use CG-SFT is the xanthan gum, which is commercially available from CP Kelco.

Examples 1-5

According to the formulations described in Table 1, O/W emulsions using C20, C22, C28, C30 fatty alcohols and policosanol were prepared in Examples 1-5, respectively. In the formulations, cetearyl glucoside was used as a co-emulsifier.

Comparative Examples 1-4

According to the formulation described in Table 1, O/W emulsions using C16, C18 and C16/C18 fatty alcohols were prepared in Comparative Examples 1-3, respectively, and an O/W emulsion without using any C16-C18 fatty alcohol was prepared in Comparative Example 4 ("control" in Figure 1).

The viscosity of the emulsions prepared in Examples and Comparative Examples was tested, and the results are also summarized in the following Table 1 and FIG. 1 .

Table 1

CE* = Comparative Example

E***＝Example

The viscosity test results in Table 1 and Figure 1 show the following significant trend: the viscosity of the emulsion varies with the length of the carbon chain of the fatty alcohol. In particular, the emulsions with C20, C22, C28 and C30 fatty alcohols and policosanol have lower viscosities than the emulsions with C16-C18 fatty alcohols.

Example 6

According to the formulation of Table 2, an O/W emulsion with a glycoside emulsifier was prepared.

Table 2

Comparative Example 6

An O/W emulsion with a glycoside emulsifier was prepared according to the formulation of Table 2. The formulation was the same as that of Example 6, except that C16-18 fatty alcohol was used instead of policosanol.

Example 7

According to the formulation of Table 3, an O/W emulsion with PEG emulsifier was prepared.

table 3

Comparative Example 7

An O/W emulsion with a PEG emulsifier was prepared according to the formulation of Table 3. The formulation was the same as that of Example 7, except that C16-18 fatty alcohol was used instead of policosanol.

Example 8

According to the formulation of Table 4, an O/W emulsion with an anionic emulsifier was prepared.

Table 4

Comparative Example 8

An O/W emulsion with an anionic emulsifier was prepared according to the formulation of Table 4. The formulation was the same as that of Example 8, except that C16-18 fatty alcohol was used instead of policosanol.

Example 9

According to the formulation of Table 5, an O/W emulsion with a polyglycerol ester emulsifier was prepared.

table 5

Comparative Example 9

An O/W emulsion with a polyglycerol ester emulsifier was prepared according to the formulation of Table 5. The formulation was the same as that of Example 9, except that C16-18 fatty alcohol was used instead of policosanol.

The viscosities of the emulsions prepared in Examples 6-9 and Comparative Examples 6-9 were measured, and the results are summarized in Table 6 below.

Table 6

Example Viscosity(cP) Example 6 10738 Comparative Example 6 27400 Example 7 51589 Comparative Example 7 90581 Example 8 23275 Comparative Example 8 49905 Example 9 31300 Comparative Example 9 39800

As shown in Table 6, when cetearyl alcohol was replaced by policosanol, which is a mixed C24-C36 fatty alcohol, the viscosity of the different O/W emulsions was greatly reduced.

As used herein, terms such as "comprising" as used herein are open-ended terms meaning "including at least" unless specifically stated otherwise.

All references, tests, standards, documents, publications, etc. mentioned herein are incorporated herein by reference. Where numerical limits or ranges are specified, the endpoints are included. Moreover, all values and subranges within numerical limits or ranges are specifically included as if explicitly written out.

The above description is proposed to enable those skilled in the art to make and use the present invention, and the above description is provided in the context of specific applications and their requirements. Various modifications to the preferred embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Therefore, the present invention is not intended to be limited to the illustrated embodiments, but to conform to the widest scope consistent with the principles and features disclosed herein. In this regard, some embodiments in the present invention may not show all the benefits of the present invention that are widely considered.

Claims (12)

1. Use of a C20-36 fatty alcohol for the preparation of an O/W emulsion having a lower viscosity than an O/W emulsion wherein the C20-36 fatty alcohol is replaced by a C16-18 fatty alcohol.
2. 2. Use according to claim 1, wherein the C20-36 fatty alcohol has a carbon chain length of 20-35, 20-34, 20-33, 20-32, 20-31, 20-30, preferably 20-30, such as 20-29, 20-28, more preferably 20-26, such as 20-24 or 20-22.
3. 3. The use according to claim 1, wherein the amount of C20-36 fatty alcohol is 0.5-10 wt%, such as 0.5-9 wt%, 1-8 wt%, 1-7 wt%, 1-6 wt%, 1-5 wt%, 1-4 wt%, 1-3.5 wt%, preferably 0.5-3 wt%, 0.8-3 wt%, or 1-3 wt%, such as 0.5-2.5 wt%, 0.5-2 wt%, 0.8-2.5 wt%, 0.8-2 wt%, 1-2.5 wt%, 1-2 wt%, based on the total weight of the emulsion.
4. 4. The use according to claim 1, wherein the O/W emulsion comprises at least one emulsifier selected from the group consisting of polyglycerol ester emulsifiers, anionic emulsifiers, PEG emulsifiers and sugar-based emulsifiers.
5. 5. An O/W emulsion comprising:

   a) 0.5-10 wt%, preferably 1-3 wt% of a C20-36 fatty alcohol, based on the total weight of the emulsion.
6. 6. The emulsion of claim 5, wherein the emulsion comprises from 1 wt% to 5 wt% O/W emulsifier based on the total weight of the emulsion.
7. 7. The emulsion of claim 6, wherein the emulsifier is selected from the group consisting of polyglycerol ester emulsifiers, anionic emulsifiers, PEG emulsifiers, and sugar-based emulsifiers.
8. 8. The emulsion of claim 5, wherein the emulsion comprises at least 90 wt%, preferably at least 95 wt%, more preferably at least 95 wt% of C20-36 fatty alcohols, wherein weight percent is with respect to all fatty alcohols contained in the total emulsion.
9. 9. The emulsion of claim 5, wherein the C20-36 fatty alcohol has a carbon chain length of 20-35, 20-34, 20-33, 20-32, 20-31, 20-30, preferably 20-30, such as 20-29, 20-28, more preferably 20-26, such as 20-24 or 20-22.
10. 10. The emulsion of claim 5, wherein the C20-36 fatty alcohols are mixtures and the amount of C20-30 fatty alcohols in the C20-36 fatty alcohols is greater than 30 wt%, 40 wt% or 50 wt%, preferably greater than 60 wt%, greater than 70 wt%, more preferably greater than 80 wt%, greater than 90 wt%, greater than 95 wt%, greater than 99 wt%.
11. 11. The emulsion of claim 5, wherein the amount of C20-36 fatty alcohol is 0.5-9 wt%, 0.5-8 wt%, 0.5-7 wt%, 0.5-6 wt%, 0.5-5 wt%, 0.5-4 wt%, 0.5-3.5 wt%, 0.8-9 wt%, 0.8-8 wt%, 0.8-7 wt%, 0.8-6 wt%, 0.8-5 wt%, 0.8-4 wt%, 0.8-3.5 wt%, 1-9 wt%, 1-8 wt%, 1-7 wt%, 1-6 wt%, 1-5 wt%, 1-4 wt%, or 1-3.5 wt%, preferably 0.5-3 wt%, 0.8-3 wt%, or 1-3 wt%, such as 0.5-2.5 wt%, 0.5-2 wt%, 0.8-2.5 wt%, 0.8-2 wt%, 1-2.5 wt%, 1-2 wt%, 1-2.5 wt%, based on the total weight of the emulsion.
12. 12. A method of preparing an O/W emulsion having a lower viscosity than an O/W emulsion having a C16-18 fatty alcohol, wherein the O/W emulsion is prepared using a C20-36 fatty alcohol, preferably in place of the C16-18 fatty alcohol.